Design for a pen



FIG. 1 is a right front perspective view for a pen showing my new design;

FIG. 2 is a top plan view;

FIG. 3 is a front elevational view;

FIG. 4 is a right side elevational view;

FIG. 5 is a left side elevational view;

FIG. 6 is a rear elevational view;

FIG. 7 is a bottom plan view; and

FIG. 8 is a right side elevational view thereof with the writing tip in its extended position. 

The ornamental design for a pen, as shown and described. 